1. A piezoelectric thin-film resonator comprising:
a piezoelectric thin film which includes aluminum nitride containing Sc and which has a concentration distribution such that a concentration of Sc is non-uniform in a thickness direction of the piezoelectric thin film;
a first electrode;
a second electrode facing the first electrode across the piezoelectric thin film; and
a substrate supporting a piezoelectric vibrating section defined by the piezoelectric thin film and the first and second electrodes.
2. The piezoelectric thin-film resonator according to claim 1, wherein the piezoelectric thin film is a multilayer film including a plurality of stacked layers having different Sc concentrations.
3. The piezoelectric thin-film resonator according to claim 2, wherein the plurality of stacked layers include an Sc-free aluminum nitride layer and an Sc-containing aluminum nitride layer.
4. The piezoelectric thin-film resonator according to claim 1, wherein the concentration of Sc in the piezoelectric thin film varies continuously in the thickness direction thereof.
5. The piezoelectric thin-film resonator according to claim 1, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration higher than that of the side portions.
6. The piezoelectric thin-film resonator according to claim 2, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration higher than that of the side portions.
7. The piezoelectric thin-film resonator according to claim 3, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration higher than that of the side portions.
8. The piezoelectric thin-film resonator according to claim 4, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration higher than that of the side portions.
9. The piezoelectric thin-film resonator according to claim 5, wherein the first electrode defines a lower electrode, the second electrode defines an upper electrode, and the piezoelectric thin film includes a surface portion which is in contact with the upper electrode and which includes aluminum nitride containing no Sc.
10. The piezoelectric thin-film resonator according to claim 1, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration lower than that of the side portions.
11. The piezoelectric thin-film resonator according to claim 2, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration lower than that of the side portions.
12. The piezoelectric thin-film resonator according to claim 3, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration lower than that of the side portions.
13. The piezoelectric thin-film resonator according to claim 4, wherein the piezoelectric thin film includes side portions which are each in contact with a corresponding one of the first and second electrodes and an approximate center of the piezoelectric thin film in the thickness direction thereof has an Sc concentration lower than that of the side portions.
14. The piezoelectric thin-film resonator according to claim 3, wherein one of the layers that is in contact with the first electrode and one of the layers that is in contact with the second electrode are Sc-containing aluminum nitride layers and one of the layers that is located at the approximate center of the piezoelectric thin film in the thickness direction thereof is an Sc-free aluminum nitride layer.
15. The piezoelectric thin-film resonator according to claim 1, wherein the concentration of Sc in the piezoelectric thin film ranges from about 0.5 atomic percent to about 24 atomic percent.
16. The piezoelectric thin-film resonator according to claim 2, wherein the concentration of Sc in the piezoelectric thin film ranges from about 0.5 atomic percent to about 24 atomic percent.
17. The piezoelectric thin-film resonator according to claim 3, wherein the concentration of Sc in the piezoelectric thin film ranges from about 0.5 atomic percent to about 24 atomic percent.
18. A method for producing a piezoelectric thin film comprising forming an Sc-containing aluminum nitride layer by performing a two-target sputtering process using a first target made of Al and a second target made of ScN such that the Sc-containing aluminum nitride layer has a concentration distribution such that the concentration of Sc is non-uniform in a thickness direction thereof.
19. A method for producing a piezoelectric thin film, comprising forming an Sc-containing aluminum nitride layer in an atmosphere containing at least a nitrogen gas by performing a sputtering process using a composite target including an Al target body including a plurality of recessed portions in a surface thereof and Sc target portions located in the plurality of recessed portions such that the Sc-containing aluminum nitride layer has a concentration distribution such that the concentration of Sc is non-uniform in a thickness direction thereof.
20. A method for producing a piezoelectric thin film, comprising forming an Sc-containing aluminum nitride layer in an atmosphere containing at least a nitrogen gas by performing a sputtering process using a composite target including an Al target body including a perforation and an Sc portion located in the perforation such that the Sc-containing aluminum nitride layer has a concentration distribution such that the concentration of Sc is non-uniform in a thickness direction thereof.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A sub-ducting apparatus comprising a sub-duct and a remotely operable path-finding element arranged to facilitate insertion of the sub-duct into a duct.
2. An apparatus as claimed in claim 1 in which the sub-duct is an elongate sleeve.
3. An apparatus as claimed in claim 1 wherein the path-finding element is a path-finding head.
4. An apparatus as claimed in claim 3 wherein the head is detachable.
5. An apparatus as claimed in claim 3 in which the head is outwardly deformable.
6. An apparatus as claimed in claim 4 in which the head includes a seal activated by pressurisation of the sub-duct.
7. An apparatus as claimed in claim 5 in which the head is outwardly deformable at the front end.
8. An apparatus as claimed in claim 5 or claim 6 in which the head is outwardly deformable at a portion set back from the front end.
9. An apparatus as claimed in claim 1 in which the head has a cutting portion at the front end.
10. An apparatus as claimed in claim 9 in which the cutting portion is a chisel portion.
11. An apparatus as claimed in claim 9 in which the cutting portion is a rotational cutter.
12. An apparatus as claimed in claim 11 in which the cutter is activated by relative movement of the sub-duct and the cutter.
13. An apparatus as claimed in claim 12 in which a helical thread translates linear movement of the sub-duct to rotational movement of the cutter.
14. An apparatus for advancing a sub-duct into a main duct comprising apparatus as claimed in any preceding claim and means for advancing it.
15. A method of inserting a sub-duct into a duct comprising advancing the sub-duct into the duct and remotely operating a path-finding element on the sub-duct to facilitate the insertion thereof.
16. (canceled)